Opioids represent one of the key pillars in postoperative pain management, but their use has been associated with a variety of serious side effects. Thus, it is crucial to investigate the timing and course of opioid administration in order to ensure a best efficacy to side-effect profile. The aim of our article was to investigate the analgesic effects of locally administered morphine sulfate (intraplantar) in a carrageenan-induced inflammation model in rats. After carrageenan administration, the rats were divided into 10 equal groups and were injected with either morphine 5 mg/kg or 0.9% saline solution at different time intervals, depending on the assigned group. The analgesic effect was assessed through thermal stimulation. Our results showed that paw withdrawal time was significantly higher in rats treated with morphine compared to those in the control group 9.18 ± 3.38 compared to 5.14 ± 2.21 seconds, p=0.012). However, differences were more pronounced at certain time intervals post-carrageenan administration (at 180 minutes compared to 360 minutes, p=0.003 and at 180 minutes compare to 1440 minutes p<0.001), indicating that efficacy varies depending on the timing of treatment. In conclusion, our findings support the hypothesis that locally administered morphine may alleviate pain under inflammatory conditions and underscores the importance of considering treatment timing when evaluating the analgesic effect.
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Increased Susceptibility to Postoperative PCA Morphine-Induced Respiratory Depression in a Patient with an Undiagnosed Traumatic Porencephalic Cyst – A Case Report
Introduction: Patient-controlled analgesia with morphine is routinely used for postoperative pain management. Due to the safety profiles of the technique, which are patient/disease related or technique/equipment related, severe respiratory depression requiring opioid antagonists or airway management are uncommon.
Case presentation: The case of a patient with right colon carcinoma who was operated on for hemicolectomy under general anaesthesia and who presented with apnoea, after postoperatively receiving an initial bolus of 1mg of morphine. A large post-traumatic porencephalic cyst of the left brain hemisphere, previously undiagnosed, was found on the computed tomography scan. We excluded human errors, technique and equipment factors, and the patient did not have any other predisposing conditions like sleep apnoea, obesity, recent head injury or concurrent use of other sedatives. Previously the patient had been entirely asymptomatic, and her increased susceptibility to respiratory depression was the only clinical manifestation of porencephaly.
Conclusion: Adult acquired porencephaly is seldom reported in the literature, clinical manifestations depending on the location and size of the cyst. In the present reported case, increased susceptibility to low-dose opioids might be associated with the structural and functional reorganisation of the brain after head trauma with the occurrence of the porencephalic cyst of the brain.